The development trend of optical transmission technology presents a single channel higher rate (e.g. single channel 400 G/1 T transmission), a higher spectrum efficiency and a high order modulation format, and therefore the most clear-cut and important direction of optical transmission development is still to continue to improve the rate. The high speed transmission faces many restrictions which mainly have two aspects: on the one hand, the optical transmission technology develops towards high spectrum efficiency convergence transmission and high speed service interface transmission; if the spectrum efficiency cannot be improved continuously, it makes little sense to aggregate low speed to high speed and then to transmit; however, since there can be still a high speed Ethernet interface at a client side, a transmission problem of a high speed interface should be still considered, and 400 G will be a critical point of spectrum efficiency limitation; on the other hand, the optical transmission technology develops towards long distance (long span and multi-span), and although a system OSNR can be improved by means such as low loss fibre, low noise amplifier and reducing span interval, the improvement is limited and is difficult to make a significant breakthrough, and it is difficult to implement in engineering.
As the increasing demand for bearer network bandwidth, beyond 100 G technology becomes a solution to the bandwidth increasing demand, and whether it is 400 G or 1 T above 100 G, wavelength division multiplexing (referred to as WDM) of a traditional 50 GHz fixed grid cannot provide an enough spectrum width to achieve the beyond 100 G technology. Because of the defect of the fixed grid, it is put forward that a wider flexible grid is needed.
In the related art, beyond 100 G multi-rate hybrid transmission and beyond 100 G modulation code pattern flexibility lead to different channel bandwidth demands, and if each channel is specified an appropriate bandwidth, the system bandwidth can be made full use of, thus producing a flexible grid system. On the basis that the demands of a superspeed WDM system for continuously increasing demand for the bandwidth, the demand for flexible grid technology is introduced; however, many problems such as how to effectively plan and manage the spectrum, and the compatibility of the current system are all to be solved.
In view of the problem of how to effectively plan and manage the spectrum after introducing the flexible grid technology in the related art, no effective solution has been proposed so far.